New Scientist reports an
ultra-thin "polymorphous" (polycrystalline?) silicon solar cell coming
in at one micrometer thick and potentially as cheap as 1 euro per peak
watt. On top of this, it's flexible and can be rolled. (Hat tip:
Slashdot.)

This leapfrogs the current contender for price/performance
leadership, the titanium-dioxide technology used by NanoSolar (though NanoSolar
appears to have a greater margin for price cuts). The extreme reduction
in material required should cut the energy-payback time by a large
fraction, probably to less than a year. The efficiency is not great at
7%, but cost more than makes up for this; the creators hope they can
reach 10%. If they can do this without increasing the cost/area, the
cost will fall to less than $1/Wpeak.

Insolation
over much of the continental US runs between 120 and 200 kcal/cm2/yr,
so selecting values in that range:

Insolation,
kcal/cm2/yr

Insolation,
kWH/m2/yr

Energy yield,
kWH/m2/yr

Cost/m2

Interest
rate

Lifespan.
years

Energy cost,
cents/kWH

120

1394.67

97.63

$123.80

7%

25

10.8

160

1859.56

130.17

$123.80

7%

25

8.1

200

2324.44

162.71

$123.80

7%

25

6.4

This appears to be competitive with flat-rate grid power, and extremely
competitive with daytime afternoon peak rates. Panels at this price
could begin replacing peaking generation in the Southwest as soon as
they went into production. For the USA, tax considerations make solar
even more favorable for homeowners. Mortgage interest is
tax-deductible, while utility costs are after-tax. If the full added
cost of the solar system is mortgaged and the buyer's marginal tax rate
is 28%, the cost of the homeowner's own energy consumption falls to less
than 8 cents per kWH.

Economic analysis: At 7% efficiency and $1.34/Wpeak at a solar flux
of 1000 W/m2, the new cells would cost $93.80/m2.
If we assume that encapsulation and other costs run to $30/m2,
covering the roof of a 2000 sf, 2-story house (~90 m2) with
such cells would cost roughly $11,000; this roof would generate 6300
watts in peak sunlight, of which perhaps 6 kW could be converted to AC
for use locally or on the grid.

What could this do?

The impervious area of the United States (roughly the area of Ohio)
receives on the order of 500 quads of solar energy per year. If this
could all be captured and 7% converted to electricity, that is 35 quads
of electricity. In contrast, all coal- and nuclear-produced electricity
amounts to less than 10 quads per year, and the petroleum-derived power
delivered to the wheels of all US vehicles is approximately
5.5 quads/year (15.04 TBTU/day * 0.365). Energy from solar would be
cheaper than petroleum, and plug-in hybrids could turn it into a direct
replacement for imported oil. An investment of $100 billion per year
would purchase ~800 million m2 of panels, which would produce
~100 billion KWH (0.34 quads) of electricity every year. In fifteen
years solar electricity could replace all petroleum-derived energy used
by motor vehicles; adding another $100 billion/year would generate
enough to replace all coal and nuclear electricity over roughly 30
years.